PROJECT SUMMARY Rhode Island (RI) has one of the highest rates of opioid overdose death in the United States and has been a leader in innovative strategies to reduce opioid overdose deaths. In March 2017, the Rhode Island (RI) Department of Health (RIDOH) and the RI Department of Behavioral Health, Developmental Disabilities, and Hospitals (BHDDH) released hospital and emergency department (ED) treatment standards for care of adult patients with opioid use disorder and opioid overdose: Levels of Care for RI Emergency Departments and Hospitals for Treating Overdose and Opioid Use Disorder (Levels of Care). These standards specify three levels for hospital and ED treatment of opioid use disorder, overdose prevention, referral to treatment, and epidemiologic surveillance. Each of the three Levels of Care (LoCs) require EDs to prescribe naloxone, provide peer recovery support services, and offer referrals to treatment for patients that have experienced an opioid overdose. Facilities certified at the highest level (Level 1) provide more comprehensive treatment services, including initiation of medication for addiction treatment (MAT). Individual components of the LoCs have been examined, but the effectiveness of the state?s overall policy has not been evaluated. A rigorous policy evaluation is needed to inform ongoing policy, practice, and strategy. Since implementation of the statewide-mandate, there has been high reported offering-of-services to patients treated after opioid overdose, but uptake of ED behavioral counseling, MAT initiation, and referral to treatment have not significantly increased (<50% of overdose cases in EDs receive all recommended components of post-overdose care). Despite these gaps, RI?s rate of opioid overdose has plateaued in recent years despite rising rates nationally and pilot data suggest that policy changes have resulted in increased treatment engagement after an ED visit for opioid overdose. Given the fast pace and high stakes of the opioid epidemic, we will simultaneously examine both the implementation and effectiveness of RI?s policy in a fully powered type III implementation-effectiveness study conducted at 9 EDs throughout RI. These 9 EDs care for >95% of all opioid overdoses that present to RI EDs annually (n~1500), creating tremendous opportunity to prevent opioid overdose deaths and also evaluate RI?s standards of care. Investigators from RI?s largest health care system, Brown University?s School of Public Health, and RIDOH are partnering to perform a hybrid implementation-effectiveness study that will: (1) refine and test an implementation strategy that aims to improve the fidelity of ED post-overdose care as it relates to the state?s Levels of Care policy, and (2) to test the effectiveness of policy-driven ED-based post-overdose care. We will specifically target implementation of 4 ED metrics: naloxone received at discharge; receipt of peer recovery support services; ED referral to treatment; and initiation of MAT in the ED.